<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear John, Julia and all respondents:<div><br></div><div>Thank you all for your helpful feedback. We now have a reasonable procedure to use when the refurbished pump and bonnet valve kit both arrive. Summarizing from what we learned and from the collective responses: PPE: disposable tyvek suit + C-filtered respirator, treating any volatiles as nasty - perhaps carcinogenic, and changing gloves often. Treating wipes and gloves as hazardous waste. Snorkel exhaust and cleanroom vacuum for dust, foil capping and bagging of the components, and brass wire brush / solvent+wipes / LN2 for foreline cleaning in the fume hood. We will document the shipping materials for the returned pump with the source gases used (SF6, C4F8) and include the EDS analysis (also found out that Oerlikon is familiar with the residue and accepts this back properly capped). Going forward: Make sure all the heater elements are working, along with temperature interlocks, and keep your eyes on it for periodic maintenance. Also: PM the system or budget for pump replacement before the thing blows up and the core return has no value.</div><div><br></div><div>FYI: Among the responses, I received verification for why it is so important to pay attention to such a large pump going out of balance with caked-on materials:</div><div><span class="Apple-style-span" style="color: rgb(31, 73, 125); font-family: Calibri, sans-serif; font-size: 15px; ">"In the end it destroyed a $40K maglev turbo threw parts into the main chamber and the whole way back to the rough pump 25 ft away. It also bent a 2 inch thick stainless steel throttle valve and sheared off 4 ˝’” thick stainless steel bolts, and dented the side of the system from the force of the abrupt stop. </span><span class="Apple-style-span" style="color: rgb(31, 73, 125); font-family: Calibri, sans-serif; font-size: 15px; ">The only part that I kept is what remains of the central portion of the pump that had the veins (once) attached.</span><span class="Apple-style-span" style="color: rgb(31, 73, 125); font-family: Calibri, sans-serif; font-size: 15px; "> </span><span class="Apple-style-span" style="color: rgb(31, 73, 125); font-family: Calibri, sans-serif; font-size: 15px; ">Here are two pictures of how catastrophic it was. The first one (3480) is what it looked like when we unhooked the turbo. We didn’t just dump parts into the containment vessel for the turbo that is how it came apart. The other one you can see the sheared off bolts and where the clamps grabbed the gate valve. Too bad I didn’t get a picture of how bent it was. Enjoy and I hope you can fix your system before that happens.</span><span class="Apple-style-span" style="color: rgb(31, 73, 125); font-family: Calibri, sans-serif; font-size: 15px; ">" --Dave </span></div><div><div><br></div><div>Dave sent some fascinating photos of his pump, which casing thankfully contained all the schrapnel, and which looks like metal-noodle soup. </div><div><br></div><div>Labnetwork is a great resource and thank you again to colleagues who make this job so much easier because of your freely shared knowledge and experience.</div><div><br></div><div>—Ian</div><div><br><div>Begin forwarded message:</div><br class="Apple-interchange-newline"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1.0);"><b>From: </b></span><span style="font-family:'Helvetica'; font-size:medium;">John Shott <<a href="mailto:shott@stanford.edu">shott@stanford.edu</a>><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1.0);"><b>Subject: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><b>Re: [labnetwork] Bosch etch foreline and pump powder residue question...</b><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1.0);"><b>Date: </b></span><span style="font-family:'Helvetica'; font-size:medium;">November 5, 2013 9:24:21 AM MST<br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1.0);"><b>To: </b></span><span style="font-family:'Helvetica'; font-size:medium;">Ian Harvey <<a href="mailto:IRHarvey@eng.utah.edu">IRHarvey@eng.utah.edu</a>><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1.0);"><b>Cc: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><a href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a><br></span></div><br>
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Ian:<br>
<br>
While you will likely get more thorough responses from others on
this matter, let me share some or our experiences in this area. In
particular, these tools generate a lot of polymer. The same
chemistry that you are relying on generating the polymer on your
wafers during half of the switched etch/deposition process is also
going to produce a low-grade polymer everywhere else. Much of the
polymer that you find in the foreline tends to be rather gummy and
difficult to remove ... at least that is our experience. Many (but
not all) machines have heated turbo pumps and I believe that had
been found to be pretty effective in terms of minimizing polymer
build up in one of your most expensive components on these tools.
One of our machines has a water cooled trap between the heated turbo
and the remainder of the foreline ... but, to be honest, that trap
has not proven to be particularly effective in our case.<br>
<br>
Because the forelines tend to get pretty well coated with a sticky,
gummy polymer, we have found them to be pretty difficult to clean.
One "trick" that seems to work pretty well in the case of the
forelines is to very carefully pour some liquid nitrogen down the
foreline which will freeze it and cause it to fall off in chunks.
This, of course, has to be done VERY carefully due to the hazards of
working with liquid nitrogen including worrying about "burns" due to
the extreme cold and asphyxiation due to displacement of oxygen in
the air. One thing that we haven't tried, but may be easier than
dealing with liquid nitrogen is to see whether packing a length of
foreline in dry ice may have the same effect ... dry ice has it's
own problems because of it's very low temperature and sublimation of
something that can displace oxygen, but it is probably easier to
handle than liquid nitrogen.<br>
<br>
While the polymer itself isn't wildly toxic or flammable in the way
that some of your pumps and forelines on other deposition tools are
(things that pump silane and DCS, for example) we treat all
forelines very carefully and, in particular, for anything that is
the least bit "powdery or dusty" make sure that we have adequate
protection to avoid inhaling or ingesting anything coming from these
pump lines.<br>
<br>
Finally, depending on the distance your foreline pump lives from the
main tool, you may need to consider upsizing the diameter of your
foreline a bit to help offset the constriction that will take place
as your get polymer build up between periodic cleaning.<br>
<br>
Good luck,<br>
<br>
John<br>
<br>
<br>
On 11/4/2013 3:36 PM, Ian Harvey wrote:
<blockquote cite="mid:18E314D3-69D5-40ED-A66F-F5BF84C8756A@eng.utah.edu" type="cite">
<div>Dear Labnetwork colleagues,</div>
<div><br>
</div>
<div>We are installing a used STS DRIE tool acquired from the used
tool market and used for Bosch-Si etch. </div>
<div><br>
</div>
<div>We are unsettled by the large amount of white powder
collected in the foreline and inside the large turbopump. The
turbo is becoming unbalanced as flakes come off, and we are
getting ready to trade in the large maglev pump for a refurb,
and clean the forelines.</div>
<div><br>
</div>
<div>Does anyone have experience with what the powder is (F-C-S-O
/ EDS analysis attached), its risks, and how to safely manage it
during pump removal, packing and declaration for shipping?</div>
<div><br>
</div>
<div>Thanks!</div>
<div><br>
</div>
<div>Ian</div>
<div><br>
</div>
<div apple-content-edited="true">
<span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; font-size: medium; ">
<div style="word-wrap: break-word;"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; font-size: medium; ">
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<div style="word-wrap: break-word;"><span class="Apple-style-span" style="orphans: 2;
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Ian R. Harvey, Ph.D.<br>
</div>
<div style="border-collapse: separate; color:
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Nanofab </div>
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<div>Micron Microscopy Core</div>
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<br>
</div>
<div>801/585-6162 (voicemail)<br>
801/581-5676 (lab main number)<br>
<a moz-do-not-send="true" href="http://www.nanofab.utah.edu/">www.nanofab.utah.edu</a></div>
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